In packaging technology, use is often made of so-called aseptic packaging techniques in order to impart longer shelf-life to and facilitate the distribution of foods and pharmaceuticals and other types of products which are particularly perishable and/or sensitive to bacterial attack. Fundamentally, the principle of the aseptic packaging technique is based on filling and sealing the product in packages which are ready for distribution, under sterile or bacteria-free conditions, in order to create the best possible circumstances for transporting and storing the product in the unopened package with retained freshness qualities during lengthy periods of time from the date of packaging and without any need for cold storage. In order that such a sterile or aseptic package be technically feasible, it is necessary that both the product which is to be packed and the material from which the package is produced are sterilized, and that the filling of the sterilized product into the package made from the sterilized packaging material be carried out under such conditions that the risk of reinfection of the product is eliminated entirely or to all intents and purposes.
A very large group of known aseptic packages for products of the type mentioned above are now most generally produced with the aid of modern, rational packaging machines of the type which, either from a web or from prefabricated blanks of a packaging material, both form, fill and seal the finished cartons or packages. Packages are produced from, for instance, a single web in that the web is first sterilized by being brought--entirely or in parts intended for sterilization--into contact with liquefied hydrogen peroxide in that the web is led down into and through a heated hydrogen peroxide bath. After passage through the hydrogen peroxide bath, the web is passed through the nip between two cooperating and co-rotating nip rollers or cylinders with whose aid any entrained surplus of hydrogen peroxide will be removed from the web and recycled to the hydrogen peroxide bath. Thereafter, the web is dried with the aid of a hot gaseous fluid, for example sterile air, which is blown towards one or both faces of the web in order to dispel any residual hydrogen peroxide. After the drying operation, the web is reformed into a tube by both longitudinal edges of the web being united with one another in a longitudinal overlap seam or joint. The tube is filled with the relevant product (previously heat-treated or otherwise sterilized) and is divided into closed, combined package units by repeated transverse sealings of the tube below the product level in the tube. The package units are separated from one another by transverse incisions in the transverse sealing zones and are given the desired geometric--normally parallelepipedic--final form by a final forming and sealing operation during which the double-walled triangular corner flaps of the cushion-shaped package units are folded in and sealed against the outside of adjacent package walls. In order to avoid reinfection of the sterilized product, both the sterilization of the packaging material and the package forming and filling operations are carried out in an environment screened-off from the unsterile surroundings of the package by hot sterile air operating at slight excess pressure in relation to the ambient pressure.
In the above-described manner, aseptic packages are produced which possess good mechanical strength and configurational stability and further display superior chemical and bacterial tightness properties which create every potential for readily being able to handle and store the product in an unbroken package, with retained or but insignificantly affected freshness qualities during lengthy periods of time from the date of packing.